It has been known that a synthetic resin is not endurable for a long-term use, since it is degraded by the effects of heat and light, which causes discoloration and deterioration in mechanical strength. As a countermeasure, for the purpose of preventing from the degradation of the synthetic resin, stabilization by adding a hindered amine compound, an ultraviolet absorber, an antioxidant or the like is prevailing.
Particularly, the hindered amine compound is added to the synthetic resin in order to improve weather resistance. Various hindered amine compounds, in addition to the exemplified compounds disclosed in the following Patent Documents 1 to 6, have been proposed.
On the other hand, it has been known that a sulfur-containing antioxidant can be used to improve heat resistance. For example, a synthetic resin containing a phenolic compound and a sulfur-containing compound is disclosed in the following Patent Document 7.    Patent Document 1: Japanese Examined Patent Application Publication No. 46-42618    Patent Document 2: Japanese Unexamined Patent Application Publication No. 48-65180    Patent Document 3: Japanese Unexamined Patent Application Publication No. 59-62651    Patent Document 4: Japanese Unexamined Patent Application Publication No. 1-113368    Patent Document 5: Japanese Unexamined Patent Application Publication No. 2-166138    Patent Document 6: International Publication No. WO2005/082852    Patent Document 7: Japanese Unexamined Patent Application Publication No. 60-197747